1. Field of the Invention
The present invention relates to a computer system and a backup method therefor and is suitably applied to, for example, a computer system that carries out backup of a volume that stores write data.
2. Description of the Related Art
Conventionally, for example, a snapshot function and a journal function are known as functions of a storage system.
The snapshot function is a function of storing an image of a logical volume at a certain point (e.g., a point when a snapshot acquisition request is received from a host computer). The storage system can intermittently acquire replication (backup) of data in the logical volume by periodically executing the snapshot function. When the snapshot function is used, the storage system can restore the logical volume at a point when a snapshot is acquired.
The journal function is a function of generating, in writing write data in a logical volume designated by a write command from the host computer, data (journal data) including the write data and control information concerning the writing of the write data and storing the generated journal data in a journal volume.
JP-A-2005-18738 discloses recovery processing executed, by writing journal data stored in a journal volume in a snapshot acquired by the snapshot function, at points other than a point when a snapshot is created. JP-A-2007-80131 discloses switching of a snapshot and a journal. JP-A-2007-133471 discloses operation of a restore volume for a snapshot.